What Is GitOps? Continuous Delivery to Kubernetes with ArgoCD

In traditional CI/CD pipelines, deploy commands are triggered externally and drift can occur between the cluster state and Git. GitOps treats the Git repository as the single source of truth, and ArgoCD continuously synchronizes this source with the Kubernetes cluster. This guide covers GitOps principles, ArgoCD installation, and production practices.

What Is GitOps?

GitOps is an operational model where all infrastructure and application configuration is stored in Git, and the cluster state is automatically reconciled with this configuration. It has four core principles:

• Declarative Configuration All infrastructure and application state is defined as YAML/JSON. You specify "what should exist," not "how to do it."
• Git as Single Source of Truth The Git repository is the sole source of desired state. Manual changes made in the cluster are automatically reverted.
• Automatic Synchronization Changes in Git are automatically applied to the cluster. No manual kubectl commands needed.
• Continuous Reconciliation The agent continuously compares cluster state with Git and corrects any drift.

ArgoCD Installation

ArgoCD is installed as a namespace in your Kubernetes cluster and managed via web UI, CLI, and API.

# Create namespace and install ArgoCD
$ kubectl create namespace argocd
$ kubectl apply -n argocd -f \
    https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml

# Get admin password
$ argocd admin initial-password -n argocd

# Port-forward for web UI access
$ kubectl port-forward svc/argocd-server -n argocd 8080:443

Defining an ArgoCD Application

In ArgoCD, each application is defined with an Application CRD. This resource specifies the Git repository, target cluster, and sync policy.

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: web-app
  namespace: argocd
spec:
  project: default
  source:
    repoURL: https://github.com/company/k8s-manifests.git
    targetRevision: main
    path: apps/web-app/production
  destination:
    server: https://kubernetes.default.svc
    namespace: production
  syncPolicy:
    automated:
      prune: true
      selfHeal: true
    syncOptions:
    - CreateNamespace=true

For Kubernetes fundamentals, check our Introduction to Kubernetes guide. For package management with Helm, see our Helm Chart guide. For CI/CD integration, explore our GitHub Actions guide. The ArgoCD documentation and OpenGitOps principles are valuable additional resources.

Frequently Asked Questions

Conclusion

GitOps makes Kubernetes deployment processes Git-centric, providing auditability, repeatability, and security. Set up automatic synchronization and self-healing with ArgoCD to prevent cluster drift. Keep your application manifests in a separate Git repository and limit your CI pipeline to image building only.